Electric heating device



M'a 1'4, 1940. KUHN ETAL 2,266,557

ELECTRIC HEATING DEVICE Filed Jan. 9. 1939 I l \l' I I I ll FIG-4, INVENTORS FRANK KUHN BY LAURENCE HIHQMAZ ATTORNEYS Patented May" 14, 1940 UNITED STATES ELECTRIC, HEATING DEVICE Frank Kuhn, Detroit, and Laurence H. Thomas,

Birmingham, Mich.,

assignors to American Electrical Heater Company, Detroit, Mich, a

corporation of Michigan Application January 9, 1939, Serial No. 250,034

Claims.

The invention. relates to electrical heating devices and more particularly toa construction designed primarily to be used for mounting photographic prints on suitable backing material.

The mounting of photographic prints has been improved in recent years by the use of mountin tissue which is placed between the print and the backing material and caused to form an adhesive bond between the two by the application of heat. The ordinary electric iron used for laundry purposes is not well adapted as the means for supplying the heat because it is usually operated at much higher temperatures than necessary for print mounting; and also it is usually of is a shape and size designed for laundry work.

Figure 2 is a top plan view thereof with the cover removed and shown partly in section;

Figure 3 is a vertical section on the line 3-4 of Figure 2;

' Figure 4 is an end view with cover removed;

Figure 5 is a perspective view illustrating the construction of the thermostat;

Figure 6 is a perspective view of a terminal connection.

In the preferred construction as illustrated in the drawing, l0 represents the base plate having a smooth bottom surface which is preferably elec- 4o troplated with chromium or some other suitable metal. The plate is rectangular in shape. II is the resistor unit which is held in contact with the upper-surface of the base plate by a clamping plate II of slightly smaller dimensions than the 5 base plate. The parts are held in assembled relation by two studs l3 projecting up from the base plate and preferably weldedthereto, which studs pass through apertures ll in the clamping plate and engagethe elongated hexagonal nuts 50 l5. I6 is a'rectangular cover plate having downturned peripheral flanges l1 engaging the base plate and fitting over the periphery of the clamping plate. The cover is retained in position by screws it which pass through the handle 66 bracket 20 and the cover I. and engage the threaded nutsli. 'fIhe bracket 20 has the upstanding arms Zi to-which the handle 22 is secured/and it is also provided with an elliptical guide. through which the plug or the electric cord passes. v

The resistor unit i-l consists oi two sections 24 and 25, each of which has fiat ribbon windings. The two sections areenclosed by overlying sheets of mica 26 and" 21. The ends of the ribbons in sections 24 and 25, respectively, are connected to the terminal pins as and a. At the opposite ends of the sections the ribbons are connected to the thermostat 30'. This form of connection results in the two sections 2 and 25 being connected in series whenever the thermostatic switch is closed.

3| is an insulator block secured to the upper plate I2 by retaining screws 22. 38 and 34 are spring bars arranged at an angle to one another and secured to the insulator block by the set screws which engage nuts 38 in the counterbores 21 of the insulator. The block is also provided with .holes 33 through which the ends oi the resistor ribbons are brought in order that they may beconnected to the springbsrs beneath the heads of the set screws 35. The spring bar It has an onset outer end portion-32 extending beneath the other spring bar a, the arrangement being such that the cooperating contacts and H carried by the respective bars are normally in engagement. An adjusting screw 42 extends through a threaded aperture in the .bar 34 and engages the insulator block for the purpose of making such initial adjustment in tension as is necessary so that the contacts will operate at the proper temperature. ll is a bimetallic thermostatic bar having one end secured to the base plate It, preferably by welding at the point N. The other end of the thermostatic bar has a laterally extending portion '45 terminating lust beneath the outer end of the upper spring bar 33. When the temperature of the thermostatic bar rises it warps upwardly.

and at a predetermined temperature it raises the spring bar 33 and breaks connection between the contacts 40 and ll.

At the opposite end from the thermostatic switch there is secured to the upper plate l2 the terminal insulating block II. This block'extends at an incline and is provided with the base portion 41 throughwhich the retaining screws 48 engage the upper plate. It also has an upper portion ll extending through a suitable aperture in the cover it into alignment with the guide 23. The terminal pins 2! and 2. are molded into the insulator block and project upwardly within the guide 23. %e block has a recess 50 formed therein for receiving the heads of the clamping screws til which threadedly engage the terminal pins. Conducting strips 52 are secured to the terminal pins by the contact screws and extend rearwardly through the aperture 50 and are provided at the rear end with prongs 53 between which are pinched the terminal windings of the resistor." sections.

he heating device, as above described, when used for mounting photographic prints is preferably designed to have an operating temperature of about 250 F. The device as described is of light weight and of a size and shape which is adapted to be conveniently used in the mountoif photographic prints. It is automatically maintained at the desired temperature by a thermos-tat which, while of simple construction, responds quickly to changes in temperature of the working surface. On the other hand, the thermostatic switch is so constructed as to avoid fluttering and consequently the device may be operated with a min'nnum amount of electrical disturbance created by the opening or closing of the contacts.

What we claim as our invention is:

1. An electric heating device comprising a base plate, a clamping plate, a pair of laterally spaced resistor units extending longitudinally between said plates, a thermostatic switch at one end of said clamping plate connected'to the terminals of the respective resistor units, a terminal block at the opposite end of said clamping plate, terminal loars connected to the opposite terminals of said resistor units, and a box cover having its edges engaging said base plate and secured to said clamping plate.

2. An electric heating device comprising a lease plate, a clamping plate, a resistor between said plates, an insulating bloci at one end of said clamping plate extending upward therefrom, converging spring bars secured to the top of said loloclr at laterally spaced points and having free ends in registration, cooperating contacts on the respective bars, a thermostatic member secured at one end to said Tease plate, and means extending upward from the free end of said thermostatic member for engaging one of said spring bars when said thermostatic member is warped by in- 5 creased temperatures whereby said contacts are separated.

3. An electric heating device comprising a base plate, a clamping plate having openings at one end thereof, a resistor between said plates hav- 1o ing terminal wires projecting through said openings, a. terminal insulator block secured to said clamping plate having two inclined terminal conducting pins protruding therefrom, said block having a recess adjacent said clamping plate, 15 conducting clips secured to said terminal pins within said recess and projecting through said recess, and clamping means for electrically connecting said terminal wires to projecting ends of said clips.

4. electric heating dev mernher to he heated, an e heating the came, an insulat by and extending upwardly from h to be heated, a pair of lcars having 2 secured to said insulating block in laterally spaced obliquely extending; guide grooves and having converging free ends in. registra' on, cccnerating contacts on the respective static member movable heat vice, and means operable icy s member for engaging one of Salli. said contacts are separated at a p temperatur An electric heating device coninrising abase 3v plate, a clamping plate, a resistor ice-tween. said plates having spaced longitudinally extending portions with terminals at the opposite ends of each portion, a thermostatic switch connected between terminals at one end of said resistor 40 portions, and external circuit connections at the opposite ends of said nortionsl terinined THOIi SAS 

